1. Field of the Invention
The present invention relates to an ink, a recording method employing the ink, and an apparatus charged with the ink. In particular, the present invention relates to an ink which exhibits less blurring of images recorded on a recording medium which has an ink-receiving surface layer composed of a binder and a pigment, a recording method employing the ink, and an apparatus charged with the ink.
1. Related Background Art
Conventionally, for ink-jet recording, an aqueous ink is used which comprises a water-soluble dye and an aqueous medium for solving the dye. The ink for ink-jet recording needs to meet the requirements below:
(1) The ink gives an image of sufficient density. PA1 (2) The ink dries quickly on a recording medium. PA1 (3) Feathering on a recorded image appears little. PA1 (4) The recorded image does not flow out when the image is brought into contact with water or alcohol, or is decipherable enough even if some flow-out of the ink occurs (water-fastness). PA1 (5) The ink or the recorded image has sufficient light-fastness. PA1 (6) The ink does not clog at a penpoint or an ink nozzle. PA1 (7) The ink is stably ejected during continuous recording or after interruption of recording for a long time without causing defects such as blurring of a recorded image (ejection stability). PA1 (8) The ink is stable in storage. PA1 (9) The ink does not damage members brought into contact with the ink. PA1 (10) The ink is safe for persons handling the ink, the safety including negativeness in Ames test. PA1 (11) The ink has a sufficient thermal stability, and does not adversely affect a thermal energy-generating means.
In ink-jet recording utilizing thermal energy, the ink needs further to meet an additional requirement below:
Black inks which meet the above requirements on plain paper are disclosed in Japanese Patent Application Laid-Open Nos. 1-135880 and 1-193375. A color ink for full-color image formation is disclosed in Japanese Patent Application Laid-Open No. 62-199667. The inks of prior art, however, do not necessarily satisfy all the requirements enumerated above.
In particular, in full-color image formation, a problem remains unsolved that a formed image blurs after leaving it for a long term. For full-color image recording, in order to obtain sharp images, recording mediums (coated paper) are usually used which have ink-receiving surface layer comprising a pigment and a binder. The coated paper causes significantly the above-mentioned blurring.
Of four colors including black, cyan, magenta, and yellow, the magenta color is especially liable to cause blurring, and in an extreme case, the printed letters have peripheral margins of magenta color, which impairs remarkably the image quality after leaving it for a long time.
Examples of magenta dyes are disclosed in Japanese Patent Application Laid-Open Nos. 58-176277, 59-78273, 60-81266, 62-190271, 62-199665 to 62-199667, and 1-53976. Each of these dyes has both advantages and disadvantages: some dyes are excellent in light-fastness, but give unclear color; some dyes are satisfactory in water-fastness and non-bleeding, but are poor in light-fastness; and some dyes are satisfactory in light-fastness and water-fastness, but discolor even under room conditions.
Japanese Patent Application Laid-Open No. 62-187773 discloses the use of a dye of the formula ##STR2## However, this dye has disadvantages in light-fastness and storage stability.